1. Field of the Invention
The invention relates to the field of electronic apparatus and concerns electronic units formed of several parts which are connected electrically by means of multiple contact connectors.
When an electric unit is constructed, such for example as an apparatus or a system, it is often necessary for practical reasons to divide it mechanically into several elements often called modules which are connected electrically by means of multiple contact connectors. Thus, for example, apparatus are very often constructed by dividing up their circuits on several flat supports called "cards" which are connected by means of multicontact connectors, or systems are formed by distributing the different functions between several apparatus which are connected together by cables provided with multipin plugs.
2. Description of the Prior Art
It is practically always necessary when an electronic unit is thus divided into modules, to transfer signals therebetween so as to ensure the overall operation. For certain categories of units, the signals to be transferred between modules are in the form of digital messages of given duration and fairly short, and a very suitable means for carrying out this transfer is the technique called "multiplex" in which the messages are emitted one after the other on a common group of conductors called "bus" to which each module is permanently connected.
In many other cases, on the other hand, the multiplex technique is not suitable for transferring signals between modules because, for example, the signals must be transmitted continuously or substantially continuously such generally as audio or video signals and most of the so called analog signals, or because the transmission of a signal cannot tolerate the delay which the multiplex is likely to introduce when the bus is occupied by a transmission in progress. A distinct connection must then be established for each signal and these connections are formed by appropriate wiring, specific to the apparatus or the system, formed, depending on the case, between the bases (i.e. the fixed parts) of the connectors serving for connecting the modules, or by means of cables connecting the modules together.
In practice the need for such wiring, often called "basket weave wiring" for the apparatus, is a source of drawbacks. During the design it is often complicated to define. It is then costly to provide because it is specific to the apparatus or system and, during adjustment, it risks having to be modified. It must be modified if, in order to adapt to new conditions of use for example, it proves necessary to modify the interconnections between modules and it does not allow, contrary to the multiplex, connections to be adapted during use to the requirements of the moment, for example, when a receiving circuit receives successively signals coming from different modules. It requires a definite base for plugging in each module, which in practice leads to providing the plugs with so called "foolproof" devices so as to prevent connecting errors and, in the case of a system formed of many apparatus, these apparatus must be connected together by numerous cables, which are expensive, cumbersome and difficult to identify when the installation must be modified.